AN APPARATUS AND A METHOD FOR TRANSPORTATION, INSTALLATION AND RETRIEVAL OF MARINE STRUCTURES

Description

FIELD OF THE INVENTION

[0001] The present invention in general, relates to an apparatus and method for transportation, installation and retrieval of marine structures.

[0002] Particularly, the present invention relates to a technology for installation and retrieval of marine structures, with the help of an apparatus where at least two vessels with adjustable buoyancy are connected so as to form a substantially V-shaped configuration.

[0003] More particularly, the present invention relates to an apparatus according to the preamble of claim 1 and to a method according to the preamble of claim 6.

TECHNICAL BACKGROUND OF THE INVENTION

[0004] In off-shore operations such as oil and gas explorations and productions, transportation, installation and retrieval of marine structures are very common. Such marine structures include off-shore platforms, jackets supporting such platforms, towers for bridges and windmills and other gravity based structures.

[0005] It is also known that such marine structures are towed to appropriate locations by vessels, barges, hulls and other bodies having adjustable buoyancy as known to persons skilled in the art. These are effectively used for installation of marine structures. Further, such vessels/barges have been effectively used for retrieval of marine structures, once their life span is over or for shifting those structures to other sites of operation.

[0006] Document US 3097495 is considered as the closest prior art and discloses the preamble of claim 1.

[0007] US patent 5607260 discloses an apparatus and a method for installation and removal of large multi ton deck packages. It teaches the use of two barges which can support a large multi ton load. A variable dimensional truss assembly is supported by the barge and forms a load transfer interface between the barge and the deck package.

[0008] The above prior art document, like most prior art techniques uses two parallel barges, which have to be interconnected with substantially large beams. This makes the arrangement less sturdy and a bit cumbersome, for loading and removing the marine structure, on and from the deck of the vessel. That apart, the top portion of the apparatus has height restriction due to the truss assembly. Hence, height restrictions exist in respect of the structure to be towed or installed or retrieved. That apart, positioning of the barges around the structure to be carried or installed or lifted is also another problem.

[0009] International PCT publication number WO 00/78604 discloses a vessel, which is a U-shaped pontoon foundation for removal and installation of marine structures. Columns are attached to the pontoon foundation, extending upwards. A tubular rotational beam is fixed to the top of the transverse pontoon and it is engaged with a bracket attached to a side of the jacket leg to be lifted. Then lifting is done with the help of a lifting frame and de-ballasting.

[0010] The above document does teach use of a U-shaped pontoon foundation which enables convenient positioning of the vessel, around a platform being installed or a platform being removed. However, the positioning, lifting and removal is dependent on a lifting frame on the top portion of the pontoon foundation, which naturally imposes a height restriction.

[0011] Hence, there has been a need for an apparatus for transportation, installation and removal of marine structures, which has a sturdy structure, requires less length of coupling beams for connecting the units of the apparatus and has free space above of the loading zone. There has been also a need for providing a methodology for transportation, installation and retrieval of marine structures which is simple and quick.

[0012] The present invention meets the above mentioned needs and other associated needs by providing an apparatus which has at least two basic units of adjustable buoyancy, which are coupled together in a substantially V-shaped form.

OBJECTS OF THE INVENTION

[0013] It is the prime object of the present invention to provide an apparatus for transportation, installation and retrieval of marine structures, which has a sturdy structure, requires lesser length of coupling beams for connecting the units of the apparatus and has the top of the loading zone free.

[0014] It is another object of the present invention to provide a methodology for transportation, installation and retrieval of marine structures which does not involve cumbersome steps and is substantially quick.

[0015] It is a further object of the present invention to provide an apparatus for installation and retrieval of marine structures which removes or substantially reduces the requirement for hinged connections and sliding parts for connecting its two basic buoyant units.

[0016] All through the specification including the claims, the words "vessels", "marine structures", "V-shaped", "barges", "cross-beams", "coupling beams", "load", "cargo", "structure" are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field known by other terms, as may be clear to persons skilled in the art. Restriction/limitation, if any, referred to in the specification, is solely by way of example and understanding the present invention. Further, it is hereby clarified that the term "riser system" should be construed in its broadest sense as applicable in subsea operations.

SUMMARY OF THE INVENTION

[0017] According to a first aspect of the present invention there is provided an apparatus for transportation, installation and retrieval of marine structures comprising at least two suitably connected vessels with adjustable buoyancy. Each of the vessels has a first end and a second end. The vessels are equipped with lifting mechanisms for lifting a marine structure on and from the apparatus. According to the invention, the vessels are connected to each other at each first end at an angle and are free at each of the second ends, thus forming a V-shape.

[0018] According to the invention the vessels are connected to each other substantially by means of cross beams at points on the deck of each vessel, in between the engaged first ends and the free second ends and so that there is room for carrying a load having a centre of gravity situated between the free second ends (8) of the vessels and the cross beam..

[0019] Further according to the invention the vessels are barges having a hull structure and equipped with ballast tanks for ballasting and de-ballasting the vessels evenly or at desired ends.

[0020] Further according to the invention consoles are provided substantially centrally on the cross beam between the barges and at symmetrically opposite locations near the free second ends on each of the barges. Preferably, the barges are arranged to lift a marine structure by winch or jacks and to lock it in position at three, four or five points on the consoles, such that the structure is secured substantially between the barges near the free second ends.

[0021] According to a second aspect of the present invention there is provided a method for transportation and installation of a marine structure by using the apparatus as described hereinbefore. The method comprises manoeuvring the vessels coupled in substantially 'V' shape into position so that the marine structure resting at its initial location is substantially placed in between the vessels close to the free second ends. Thereafter the structure is lifted and secured at a position between the vessels near the free second ends, by suitable means. Then the structure is towed to the desired location by the vessels coupled in substantially V-shape. On reaching the desired location, the structure is de-coupled from the consoles and gradually lowered to the sea bed close to the free second ends. This is done either by ballasting to desired depth or by being held by the ropes of winches present in at least three consoles on the apparatus, possibly combined with a de-ballasting the vessels for balanced operation.

[0022] According to the invention the step of lifting and securing and the structure in position for towing comprises lifting the structure by winch or jacks and locking it in position at the three, four or five points on consoles. After securing the structure to the consoles the jacks or winches may be released. Preferably the vessel is ballasted at the first ends.

[0023] Alternatively, the step in the preceding paragraph comprises ballasting the vessels to the desired depth, positioning of the structure and securing it between the vessels, de-ballasting the vessels to lift the structure so secured to the desired position, for making it ready for towing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Having described the main features of the invention above, a more detailed and non-limiting description of an exemplary embodiment will be given in the following with reference to the drawings.

Figure 1a is a plan view of the apparatus according to a preferred embodiment of the present invention.

Figure 1 b is a cross-sectional view along the line P-P in figure 1 a.

Figure 1 c is a cross-sectional view along the line Q-Q in figure 1 a.

Figure 1d is a side view of the apparatus shown in figure 1a.

Figure 2a is a plan view of the apparatus showing the coupled barges manoeuvred into position and ready to lift the load.

Figure 2b is a side view of the apparatus shown in figure 2a before loading of the structure to be transported.

Figure 2c is a side view of the apparatus shown in figure 2a after loading of the structure to be transported.

Figure 3 is an enlarged view of the view in figure 1 b also showing the structure to be transported.

Figure 4 is an enlarged view of the view in figure 1c also showing the structure to be transported.

Figure 5a is a plan view of the apparatus lifting a windmill foundation.

Figure 5b is a cross-sectional view along the lines A-A in figure 5a.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The following describes a preferred embodiment of the present invention which is purely exemplary for the sake of understanding the invention and non-limiting.

[0026] In all the figures, like reference numerals represent like features. Further, when in the following it is referred to "top", "bottom", "upward", "downward", "above" or "below" and similar terms , this is strictly referring to an orientation with reference to the sea bed, where the sea bed is horizontal and at the bottom.

[0027] It should also be understood that the orientation of the various components may be otherwise than shown in the drawings, without deviating from the principle of the invention. Furthermore, the disposition of winches, cranes supporting platforms for the marine structures are not shown, as those are not consequential to the present invention and should be understood by persons skilled in the art.

[0028] Figure 1 a is a plan view of the preferred embodiment of the apparatus 1'. It comprises two barges 1, 2 with hull structure. Each of the two barges has a first end 5 and a second end 8. The first ends 5 of the barges are connected so as to form an angle 4, while the second ends 8 are free, so that the barges 1, 2 form substantially a V-shape.

[0029] The barges 1, 2 are also connected at points 6, 7 on respective decks by rigid cross beams 3, which act as a coupling element. The barges 1, 2 are equipped with ballast tanks (not shown), for ballasting and de-ballasting and for that purpose sea water may be conveniently used. Ballasting and de-ballasting may be done evenly throughout the barges 1, 2 or at selected ends. To facilitate this, the barges are conveniently divided into several ballast chambers.

[0030] The barges 1, 2 have requisite facilities like cranes and winches (not shown) etc. suitably placed on a working platform (not shown). The barges 1, 2 are selected and placed at an angle in 'V' shape, the angle depending on the size of the article to be towed, hazard en route, the location where the article is to be delivered and so on. The barges can be towed by other vessels or they may be self-propelled.

[0031] The barges support a marine structure 10, often referred to hereinafter as load/cargo 10, along respective decks and also along the portion in between the two barges 1, 2 near the free second ends 8 of each. The barges 1, 2 can tow the marine structure conveniently to the desired location.

[0032] Suitable consoles 9 are placed on the middle portion of the cross beam 3 (best shown in figure 2a) and at one or two points more, away from the points 6, 7 on the decks of the barges 1, 2 where the cross beam 3 is connected to the barges 1, 2.

[0033] The angle 4 between the barges 1, 2 and the location of the cross beam 3 is mainly decided by the size of the cargo 10 to be transported. The rigid connections are made with generously designed heavy metal brackets and coupling beams, suitable to withstand the loads under extreme conditions while transporting. Thus an arrangement is arrived at, where a pair of barges 1, 2 coupled like a pair of tongs; act as a single floating body. A strong monolithic structure is obtained free from complication of hinges, concrete poles and so on as known in the art.

[0034] Figure 1b is a cross-section along the line P-P in figure 1 a, while figure 1c is a cross-section along the line Q-Q in Figure 1 a. Figure 1 b shows elaborately the configuration of the cross/coupling beam 3 with respect to the points 6, 7 on the decks of the barges 1, 2. Figure 3 is an enlarged view of the view shown in figure 1 b together with the load 10 to be transported.

[0035] Figure 1c shows the console 9. Figure 4 is an enlarged view of the figure 1c together with the load to be transported. This figure 4 also shows the lifting arrangement for the load 10.

[0036] Figure 1d is a side view of the apparatus which shows the consoles 9 and the cross beam 3.

[0037] When the figures 1a, 1b, 1c and 1d are seen together it would be clear that the apparatus in its simplest form does not have hinged or sliding parts. Hence, potentialities of wear and tear are reduced. Two coupling points of connection between the barges 1, 2 with a long distance in between provide good torsion stiffness for coupled barges. Further, particularly figures 1 a, 1 b and figure 3 reveal the significantly reduced dimensions of the coupling beam 3 between the barges 1, 2.

[0038] Figure 2a is a plan view of the apparatus showing the coupled bargesl, 2 manoeuvred into position. The structure 10 to be transported is seen resting at its initial location 11, usually outside a quay or in a dry dock, where the structure has either been constructed or carried by road for onward transport to its final location at sea.

[0039] Figure 2b is a side view of the apparatus in figure 2a, when the structure 10 is yet to be loaded. Figure 2c is the side view when the structure 10 after the barges have been ballasted to a greater draught and ready to lift the structure. Figure 5a is plan view of the apparatus showing lifting of GBS slabs 10 of different diameters by the apparatus. By way of example, the load here comprises GBS slabs of varying diameters. The figure 5b is a cross-sectional view along lines A-A in figure 5a.

[0040] This figure 5b in particular, unequivocally corroborates that the apparatus in accordance with the present invention can be configured to transport, install and retrieve loads of varying shape and weight. This will be explained again later.

[0041] The example chosen here shows that normally the hulls without the cargo load and with ballast compartments empty, i.e. only supporting its deck load with the beam 3 etc. will have a freeboard of more than 5.0 m and a draft of about 1.0 m. The hulls have ballast compartments distributed along its length which when filled can submerge the hulls evenly or at one side, depending on the requirement.

[0042] All the above figures are again referred to while explaining the functioning of the apparatus of the present invention.

[0043] Referring to figure 5a the elaborate functioning is described. First, the barges1, 2 coupled in 'V' shape are manoeuvred into position so that the marine structure 10 (a foundation for a windmill in this preferred example), resting at its initial location 11, is near the free second end 8 of the coupled barges 1, 2 and between the barges 1, 2. As stated before, this may be a dry dock 11 where the structure has either been constructed or carried by road for onward transport to its final location at sea. The structure 10 is yet to be lifted and secured near the middle of the open end of the tong like formation.

[0044] At the next stage, best shown in figure 5a, the foundation is lifted by winches or jacks and locked in position at, in this case, the five points on the consoles 9 during transportation. The first point is the middle point 9 of the coupling beam 3 between the two barges1, 2, and the other points being on symmetrically opposite consoles 9 on each of the barges 1, 2.

[0045] It would be particularly clear from figure 5b that the structure 10 is placed and secured between the barges 1, 2 near the free second ends 8 of the tong-like formation for towing along the sea surface. This ensures transportation with ease and safety. It would be understood to persons skilled in the art that this is equally true in respect of lifting the marine structure10 from such location and installing it on the seabed through the sea water and also for retrieving a marine structure from the sea bed.

[0046] Figure 2c is a side view of the apparatus when the barges have been ballasted to increase the draught. In this position the structure 10 is secured in place and made ready for towing. The view in figure 3 shows the stage when the structure (in this case a GBS slab) has been lifted off the surface on which it has been placed. The lifting is at least partially done by de-ballasting the barges.

[0047] Before towing commences the ballast compartments at the opposite end of the barges, i.e. towards the first end 5 of the apparatus are filled with seawater to balance the cargo load 10 and keep the hulls evenly floating. The structure 10 is now absolutely ready to be towed.

[0048] The structure 10 is towed and on reaching the scheduled location, the slab 10 is decoupled from the consoles 9 and gradually lowered to the sea bed, held by the ropes of the winches present in at least three consoles 9 for balanced operation. After proper placement of the slabs 10 on the sea bed, the winch ropes can be disengaged by any means, say by deploying an ROV and wound back, completing the operation.

[0049] Working in a reverse mode, this method and apparatus can be equally effective for retrieval of suitable marine structures from sea bed and towing those to other locations or back to a suitable location for decommission or disposal. On retrieval of the marine structure according to the present invention, it may be towed back by the apparatus of the present invention or by other vessels and this is within the scope of the present invention.

[0050] It would be clear to the person of skill that the apparatus in accordance with the present invention has the ability to lift and secure in place loads of varying dimensions. Thus, the apparatus in accordance with the present invention can be suitably configured, for its applicability on structures of varying diameters, lengths, widths, heights and shapes. To accommodate for this the angle 4, the location of the cross beam 3 and the location of the consoles 9 may need to be adjusted. To facilitate this, the cross beam 3 and the consoles 9 may be slidably arranged on the barges.

[0051] In general for a 7000 T load, ballast water needed is 6000T, when the barge is considered completely rectangular and in the example considered the draft is 3.6m. These aspects would be clear from figures 2a, 2b and 2c. In figure 2a, the draft is about 1m while in figure 2c draft is about 3.6m.

[0052] It may be noted that loading of the loads 10 can be done by various means and that is not consequential to the present invention. For example, instead of first ballasting the barges to a greater draught, then position and attach load and then de-ballast to lift the cargo, it is also possible to lift the cargo by jacks/winches and adjust the level of the barges by ballasting during the lifting. This aspect is within the scope of the present invention.

[0053] Unlike systems taught in prior art, loading and towing cargoes of significant height is not a constraint according to the present invention. This is a huge practical benefit. Decoupling and placing of the structure 10 on the seabed is a very simple process compared to what is taught in most of the prior arts where, before the cargo can be lowered to the sea bed, elaborate arrangements are required to clear the cargo from the barges. However, owing to the open 'V' shaped construction in this invention, the cargo can be simply decoupled and lowered to sea bed.

[0054] Furthermore, significantly reduced dimensions of coupling beams between barges are achieved compared to prior art. This not only saves the material, it provides a more sturdy structure due to the shorter span of the beam. Additionally, no hinged or sliding parts for joining the barges is required, which ensures less chances of failure and resulting maintenance requirement.

[0055] The present invention has been described with reference to a preferred embodiment and some drawings for the sake of understanding only and it should be clear to persons skilled in the art that the present invention includes all legitimate modifications within the ambit of what has been described hereinbefore and claimed in the appended claims.

Claims

1. An apparatus for transportation, installation and retrieval of marine structures comprising at least two inter-connected vessels (1, 2) with adjustable buoyancy, each having a first end (5) and a second end (8) and are equipped with a mechanism (3, 9) for lifting and carrying a marine structure (10), said vessels (1, 2) being connected to one another at each said first end (5) at an angle (4) and are free at each said second end (8), thus forming a V-shape, characterised in that said vessels are connected to one another substantially by means of at least one cross beam (3) at points (6, 7) on the deck of each vessel, said points being between the engaged first ends (5) and the free second ends (8), and so that there is room for carrying a load having a centre of gravity situated between the free second ends (8) of the vessels and the cross beam, that the vessels (1, 2) are barges having a hall structure and being equipped with ballast tanks for ballasting and de-ballasting the barges evenly or at desired ends, and that consoles (9) for lifting and securing the load are provided along the cross beam (3) between the barges (1,2), and at symmetrically opposite locations near the free second end (8) of each of the barges (1,2).

2. The apparatus according to claim 1, characterised in that the barges (1, 2) are arranged to lift a marine structure (10) by winch or jacks and to lock it in position at three, four or five points on said consoles (9), such that said structure (10) is secured substantially between the barges (1,2) near the free second end (8) of the barges (1,2).

3. A method for transporting and installing a marine structure by using an apparatus comprising at least two inter-connected vessels (1, 2) with adjustable buoyancy, such that said vessels are connected to one another at a first end (5) so as to form an angle (4) and are each free at a second end (8), thus forming substantially a V-shape, the method comprising:

a) manoeuvring the vessels (1, 2) coupled in substantially V-shape into position so that the marine structure (10) resting at its initial location (11), is placed substantially in between the vessels (1, 2) close to the free second ends (8); characterised in that the method further comprising:

b) lifting, securing and releasing the structure (10) while the structure (10) is at the position between the vessels (1, 2) near the free second ends (8), by lifting the structure (10) by winch or jacks and locking it in position at at least three points on consoles (9), the points being provided substantially along the middle of a cross beam (3) between the vessels (1,2) and at symmetrically opposite locations near the free second end (8) on each of the vessels (1, 2); and releasing the jacks or winches while ballasting the vessels (1,2) near the first end (5).;

c) towing the structure (10) to the desired location by the vessels (1,2) coupled in substantially V-shape;

d) on reaching the desired location, gradually lowering the structure (10) to the seabed.

4.  The method according to claim 3, characterised in that the lifting is done by ballasting the vessels to a desired depth, securing the structure (10) to the vessels and subsequently de-ballasting the vessels.

5. The method according to claim 3, characterised in that the lifting is done by ropes of winches present in at least three consoles (9) on the apparatus and de-ballasting the vessels (1, 2) for balanced operation.

6. The method according to any of the preceding claims 3 - 5, characterised by step b) comprising ballasting the vessels (1,2) to the desired depth, positioning the structure (10) and securing it between the vessels (1,2) near the free second ends (8), de-ballasting the vessels (1,2) to lift the structure (10) to a desired position, making it ready for towing.

Ansprüche

1. Vorrichtung zum Transport, zur Installation und zum Wiederauffinden von marinen Bauwerken, umfassend zumindest zwei miteinander verbundene Schiffe (1, 2) mit einstellbarem Auftrieb, wobei jedes ein erstes Ende (5) und ein zweites Ende (8) aufweist und mit einem Mechanismus (3, 9) zum Heben und Tragen eines marinen Bauwerks (10) ausgerüstet ist, wobei die Schiffe (1, 2) miteinander an jedem ersten Ende (5) in einem Winkel (4) verbunden und an jedem zweiten Ende (8) frei sind, so dass sie eine V-Form bilden, dadurch gekennzeichnet, dass die Schiffe im Wesentlichen durch zumindest einen Querbalken (3) an Punkten (6, 7) auf dem Deck jedes Schiffs verbunden sind, wobei die Punkte zwischen den miteinander verbundenen ersten Enden (5) und den freien zweiten Enden (8) sind, so dass dort ein Raum zum Tragen einer Last ist, deren Schwerpunkt zwischen den freien zweiten Enden (8) der Schiffe und dem Querbalken angeordnet ist, dass die Schiffe (1, 2) Kähne mit einer Rumpfstruktur sind und mit Ballasttanks ausgestaltet sind, um gleichmäßig oder an den erwünschten Enden der Kähne Ballast zu laden oder zu entladen, und dass Ausleger (9) zum Heben und Sichern der Last entlang des Querbalkens (3) zwischen den Kähnen (1, 2) und an symmetrisch gegenüberliegenden Orten nahe des freien Endes (8) jedes Kahns (1, 2) vorgesehen sind.

2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass die Kähne (1, 2) angeordnet sind, um ein marines Bauwerk (10) durch eine Winde oder Hebevorrichtung zu heben und sie in einer Position an drei, vier oder fünf Punkten auf den Auslegern (9) zu verriegeln, so dass das Bauwerk (10) im Wesentlichen zwischen den Kähnen (1, 2) in der Nähe des freien Endes (8) der Kähne (1, 2) gesichert ist.

3. Verfahren zum Transport und zur Installation eines marinen Bauwerks durch Verwenden einer Vorrichtung, umfassend zumindest zwei miteinander verbundene Schiffe (1, 2) mit einstellbarem Auftrieb, wobei die Schiffe miteinander an einem ersten Ende (5) verbunden sind, so dass sie einen Winkel (4) bilden und jeweils frei an einem zweiten Ende (8) sind und so im Wesentlichen eine V-Form bilden, wobei das Verfahren umfasst:

a) Manövrieren der Schiffe (1, 2), welche im Wesentlichen in einer V-Form gekoppelt sind, in Position, so dass das marine Bauwerk (10), welches an seiner ursprünglichen Position ruht, im Wesentlichen zwischen den Schiffe (1, 2) in die Nähe der freien Enden (8) angeordnet wird, dadurch gekennzeichnet, dass das Verfahren weiterhin umfasst:

b) Heben, Sichern und Freigeben des Bauwerks (10), während das Bauwerk (10) an der Position zwischen den Schiffen (1, 2) nahe der freien zweiten Enden (8) angeordnet ist, durch Heben des Bauwerks (10) durch eine Winde oder Hebevorrichtung und Verriegeln dieser in einer Position auf zumindest drei Punkten auf den Auslegern (9), wobei die Punkte im Wesentlichen entlang der Mitte eines Querbalkens (3) zwischen den Schiffen (1, 2) und an symmetrisch gegenüberliegenden Orten zwischen dem freien Ende (8) jedes der Schiffe (1, 2) vorgesehen sind; und Freigeben der Hebevorrichtung oder Winden, während die Schiffe (1, 2) in der Nähe des ersten Endes (5) Ballast laden;

c) Schleppen des Bauwerks (10) zur gewünschten Position durch die im Wesentlichen in V-Form gekoppelten Schiffe (1, 2);

d) beim Erreichen der erwünschten Position, allmähliches Absetzen des Bauwerks (10) auf den Meeresgrund.

4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass das Heben durch Ballastladen auf die Schiffe zu einer gewünschten Tiefe, Sichern des Bauwerks (10) an den Schiffen und nachfolgendes Entladen des Ballasts von den Schiffen erfolgt.

5. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass das Heben durch Seile der Winden, welche auf zumindest drei Auslegern (9) auf der Vorrichtung vorgesehen sind, und Entladen des Ballasts von den Schiffen (1, 2) für eine balancierte Arbeitsweise erfolgt.

6. Verfahren nach einem der Ansprüche 3-5, dadurch gekennzeichnet, dass der Schritt b) Laden von Ballast auf die Schiffe (1, 2) bis zu einer gewünschten Tiefe, Positionieren des Bauwerks (10) und Sichern desselben zwischen den Schiffen (1, 2) nahe der freien zweiten Enden (8), Entladen des Ballasts von den Schiffen (1, 2), um das Bauwerk (10) zu einer gewünschten Position zu heben, und Fertigmachen zum Schleppen umfasst.

Revendications

1. Appareil pour le transport, l'installation et la récupération de structures marines comprenant au moins deux navires interconnectés (1, 2) à flottabilité ajustable, chacun ayant une première extrémité (5) et une seconde extrémité (8) et étant équipés d'un mécanisme (3, 9) pour lever et transporter une structure marine (10), lesdits navires (1,2) étant connectés l'un à l'autre à chacune desdites premières extrémités (5) selon un angle (4) et sont libres à chacune desdites secondes extrémités (8), formant ainsi une forme en V, caractérisé en ce que lesdits navires sont connectés l'un à l'autre pour l'essentiel par des moyens d'au moins une traverse (3) aux points (6, 7) sur le pont de chaque navire, lesdits points étant entre les premières extrémités engagées (5) et les secondes extrémités libres (8) et de façon à ce qu'il y ait de la place pour transporter une charge ayant un centre de gravité situé entre les secondes extrémités libres (8) des navires et la poutre transversale, en ce que les navires (1, 2) sont des barges ayant une structure de coque et sont équipés de réservoirs de ballastage pour ballaster et déballaster les barges de manière homogène ou à des extrémités souhaitées, et en ce que les consoles (9) pour lever et arrimer la charge sont disposées le long de la traverse (3) entre les barges (1, 2) et à des endroits symétriquement opposés près de la seconde extrémité libre (8) de chacune des barges (1, 2).

2. Appareil selon l'une quelconque des revendications 1, caractérisé en ce que les barges (1, 2) sont disposées pour lever une structure marine (10) au moyen d'un treuil ou de crics et pour la verrouiller en trois, quatre ou cinq points sur lesdites consoles (9), de façon à ce que ladite structure (10) soit pour l'essentiel arrimée entre les barges (1, 2) près de la seconde extrémité libre (8) des barges (1, 2).

3. Procédé pour transporter et installer une structure marine en utilisant un appareillage comprenant au moins deux navires interconnectés (1, 2) à flottabilité ajustable, tel que lesdits navires sont connectés l'un à l'autre à une première extrémité (5) de façon à former un angle (4) et sont chacun libres à une seconde extrémité (8), formant ainsi pour l'essentiel une forme de V, le procédé comprenant les étapes consistant à :

a) manoeuvrer les navires (1, 2) couplés selon une forme substantiellement en V en position de façon à ce que la structure marine (10) se trouvant à son emplacement initial (11) soit placée pour l'essentiel entre les navires (1,2) près des secondes extrémités libres (8) ; caractérisé en ce que le procédé comprend en outre les étapes consistant à :

b) lever, arrimer et libérer la structure (10) pendant que la structure (10) est en position entre les navires (1, 2) près des secondes extrémités libres (8), en levant la structure (10) au moyen d'un treuil ou de crics et en la verrouillant en position en au moins trois points sur des consoles (9), les points étant disposés pour l'essentiel le long du milieu d'une poutre transversale (3) entre les navires (1, 2) et en des emplacements symétriquement opposés près de la seconde extrémité libre (8) sur chacun des navires (1, 2) ; et libérant les crics ou treuils tout en ballastant les navires (1, 2) près de la première extrémité (5) ;

c) remorquer la structure (10) jusqu'à l'emplacement souhaité au moyen des navires (1, 2) couplés selon une forme pour l'essentiel en V ;

d) atteindre la destination souhaitée, en abaissant graduellement la structure (10) sur le fond marin.

4. Procédé selon la revendication 3, caractérisé en ce que le levage est effectué en ballastant les navires à une profondeur désirée, en arrimant la structure (10) aux navires et en déballastant ultérieurement les navires.

5. Procédé selon la revendication 3, caractérisé en ce que le levage est effectué au moyen de câbles de treuils présents dans au moins trois consoles (9) sur l'appareillage et en déballastant les navires (1, 2) pour une opération équilibrée.

6. Procédé selon l'une quelconque des revendications précédentes 3 - 5, caractérisé par l'étape b) comprenant le ballastage des navires (1, 2) à la profondeur désirée, le positionnement de la structure (10) et son arrimage entre les navires (1, 2) près des secondes extrémités libres (8), le déballastage des navires (1, 2) pour lever la structure (10) en une position souhaitée, la rendant prête au remorquage.

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